Seems to have been originally only a common noun derived from bazein to speak, and to have signified any prophet or speaker. In later times, however, Bacis was regarded as a proper noun, and the ancients distinguish several seers of this name.
1. The Boeotian, the most celebrated of them, was believed to have lived and given his oracles at Heleon in Boeotia, being inspired by the nymphs of the Corycian cave. His oracles were held in high esteem, and, from the specimens we still possess in Herodotus and Pausanias, we see that, like the Delphic oracles, they were composed in hexameter verse. (Paus. iv. 27. § 2, ix. 17. § 4, x. 12. § 6, 14. § 3, 32. § 6; Herod. viii. 20, 77, ix. 43; Aristoph. Pax, 1009 with the Schol., Equit. 123, Av. 907.) From these passages it seems evident, that in Boeotia Bacis was regarded as an ancient prophet, of whose oracles there existed a collection made either by himself or by others, similar to the Sibylline books at Rome; and, in fact, Cicero (de Divin. i. 18), Aelian (V.H. xii. 25), Tzetzes (ad Lycoph,. 1278), and other writers, mention this Bacis always as a being of the same class with the Sibyls.
2. The Arcadian, is mentioned by Clemens of Alexandria as the only one besides the Boeotian. (Strom. i. p. 333.) According to Suidas, he belonged to the town of Caphya, and was also called Cydas and Aletes. (Comp. Tzetzes, ad Lycoph.. l.c.)
3. The Athenian, is mentioned along with the two others by Aelian, Suidas, Tzetzes, and the Scholiast on Aristophanes. (Pax, 1009; comp. Perizon. ad Aelian, V. H. xii. 25.)